Prophylactic administration of two different bolus doses of phenylephrine for prevention of spinal-induced hypotension during cesarean section: A prospective double-blinded clinical study

Background: Hypotension following spinal anesthesia during cesarean delivery can cause adverse maternal and fetal effects. Phenylephrine has been found to be a potent vasopressor in preventing spinal-induced hypotension during cesarean section (CS) without fetal acidosis. Material and Methods: In this prospective double-blinded study, 120 parturients of ASA grade I and II posted for CS under spinal anesthesia were randomized into three groups of 40 each: group P-0, group P-75, and group P-100. The primary objective was to study the influence of two different doses of phenylephrine on the incidence of spinal-induced hypotension during cesarean section. Corelation of postural variations in baseline hemodynamic data with observed degree of orthostatic hypotension to predict intraoperative hypotension, requirement of rescue vasopressors, and incidence of side effects and neonatal outcome were the secondary outcome measures. Statistical analysis was done with SPSS version 16 using student t test, ANOVA, and Chi-square test. Results: Incidence of hypotension was 70%, 25%, and 17.50% in P-0, P-75, and P-100 groups (P < 0.001), respectively. Maximum change in systolic blood pressure paralleled the increasing doses of prophylactic phenylephrine which was highest in P-100 group as compared to P-75 and P-0 groups. Incidence of bradycardia was higher in group P-100 than groups P-75 and P-0. There were no other significant differences among the three groups. Conclusion: Prophylactic bolus dose of phenylephrine 75 mcg was found to be effective for the management of spinal-induced hypotension and should be preferred over 100 mcg which causes significant bradycardia and reactive hypertension.